I was interested in the article by David Bowman in the last issue
(Issue 10,
Introduced grasses, triumph or Trojan horse?
see link below
). I have just completed an Honours project investigating
infestation of gamba grass in Wildman River National Park in the
NT. Readers might be interested to know some of my findings.
The bad news: Despite the belief that establishment requires
disturbance, gamba grass can grow quite readily in burnt and
unburnt savanna habitats, regardless of whether the soil surface is
broken. Additionally, it grows well in upland Melaleuca forests and
floodplain margins, but in these habitats disturbance enhances
establishment. This finding calls for extensive control measures
across a wide variety of habitats.
A mature gamba grass plant in the Darwin region has the potential
to produce up to 250,000 seeds in one season. With viability of
between 48-64 per cent, that is a lot of seeds!
The good news: Seed viability declines to a minimum within 12
months of seed shed. This is a potential weakness in the
plant’s reproduction strategy and could be a key to its
control. In management terms, it can mean that if a plant or
infestation is removed or poisoned before it seeds, there is a very
good chance that the area will be free of gamba within a year or
two.
The Eucalypt savannas of the Top End are in danger.
Gamba grass is a problem that will affect all rural and semi-rural
landowners and any member of the public that expects to appreciate
the natural beauty of the Top End. If control measures are not
implemented now, the problems are likely to accelerate to a point
where these measures are no longer achievable. Let’s not sit
and wait.
Trish Flores
Parks & Wildlife Commission of the NT
